Semester_2/OOP/Lab_06/Exercise4/Circle.java
public class Circle extends Shape {
    private double radius = 1.0;

    public Circle() {
        super();
    }

    public Circle(double radius, String color, boolean filled) {
        super(color, filled);
        this.radius = radius;
    }

    public double getRadius() {
        return this.radius;
    }

    public void setRadius(double radius) {
        this.radius = radius;
    }

    public double getArea() {
        return Math.PI * this.radius * this.radius;
    }

    public double getPerimeter() {
        return 2 * Math.PI * this.radius;
    }

    @Override
    public String toString() {
        return "Circle[color = " + getColor() + ", filled = " + isFilled() + ", radius = " + this.radius + ", area = "
                + getArea() + ", perimeter = " + getPerimeter() + "]";
    }
}